Figure 2.
Mapping ATM phosphorylation sites on Chk2. (A) Domain structure of human Chk2. SQ/TQ, Ser-Gln and Thr-Gln cluster domain; FHA, fork-head associated domain; Kinase, kinase domain; O, SQ and TQ motifs. (B) Phosphorylation of the SQ/TQ-cluster domain on Chk2 by ATM. Immunoprecipitates with anti-FLAG from 293T cells transfected with FLAG-ATM were incubated with [γ-32P]ATP and GST-SQ/TQ, GST-ΔSQ/TQ, or GST. Regions of SQ/TQ and ΔSQ/TQ fused to GST are shown in A. Proteins were resolved by SDS-PAGE and visualized by autoradiography.